Cheating Viruses and Game Theory

The temptation to cheat appears to be a universal fact of life.
Regrettably too common among human beings, cheating has also been
found among many other animals, including monkeys, birds and fishes.
In a series of laboratory experiments, evolutionary biologist Paul
Turner at Yale University has now discovered cheaters among viruses.
Turner applied game theory, a branch of mathematics that analyzes
competitive interactions, to the experimental evolution of a virus
that preys on bacteria, the phi-6 bacteriophage. His analysis
revealed that some of the viruses had evolved to replicate more
quickly, apparently by usurping the resources supplied by other
viruses—in other words, by cheating. The study is the first to
demonstrate the evolution of irrational, selfish behavior in a
biological system.